Dispensing a drug or other bioactive substance within a digestive tract of a body poses at least two basic issues. First, one must identify the proper location within the digestive tract for dispensing the drug from the capsule. Second, the drug must be selectively released at the identified location and/or at an appropriate point in time.
In one example, inert, ingestible medical capsules are known which are capable of sensing a single condition such as temperature or pH within the digestive tract and then transmitting that sensed temperature or sensed pH data to a receiver located remotely outside of the body. This sensed data can help identify a body location for dispensing a drug. Since the capsule is inert, i.e. non-digestible, the capsule can be reused for subsequent procedures. Use of this medical capsule requires the patient to be located closely to the remote data receiver for an extended period of time to insure that the sensed data is properly transmitted to the remote receiver. Sensor-only capsules are not capable of dispensing a drug from the capsule.
In another example, other inert, ingestible medical capsules are known which can both sense biologic data and selectively dispense drugs within the digestive tract. The capsule is ingested and initially operates much like the previously described sensor-only capsules, transmitting data such as temperature or pH to a receiver remotely located outside the body. Upon the desired sensed data being detected, a transmitter remotely located outside the body sends an activation signal to a receiver within the capsule to initiate dispensing of the drug from the capsule within the digestive tract. Additional means such as known radiographic techniques can be used to further identify the location of the capsule in relation to the sensed data. Accordingly, these conventional drug dispenser capsules require the patient to be close to a transmitter/receiver remotely located outside of the body to perform the transmitting and receiving functions associated with the capsule.
Accordingly, conventional intrabody drug dispensers have several limitations. First, conventional drug dispensing capsules require a transmitter for transmitting sensed data while in the digestive tract and must be used with a remote receiver for receiving the transmitted data. Conventional drug dispenser capsules also require a receiver for receiving a drug-dispensing activation signal and must be used with a remote transmitter for transmitting the activation signal to the receiver within the capsule. In some case, these requirements force the patient to remain relatively stationary for a protracted period of time during the procedure to insure adequate proximity to the remote transmitter/receiver. The remote transmitter and/or receiver also must be used in association with a human event manager and/or a computer-driven management system to determine what signals are received and what signals should be sent, as well as when to do so. This active human management or computer-driven management raises the cost of the sensing or dispensing procedure and again requires the patient to be located adjacent the computer equipment or a human for an extended period of time. Finally, the mandatory constraint of placing a transmitter and/or receiver within the capsule makes the capsule bulkier, requires a larger capsule, or less space is available to accommodate other functional modules such as drug storage, sensors, etc.